Method of transvaginal sterilization

ABSTRACT

A method for sterilization of females has been devised in which one or more hypodermic needles can be inserted into the uterus to a predetermined position or location at the uterine cornu and the internal tubal ostra followed by injecting a sclerosing agent which produces a chronic lesion at that point. The entire needle assembly is characterized by slidable mounting of the needle or needles within a guide or sleeve projecting forwardly from a disposable cartridge, and a hand-held actuator is provided to selectively control successive advancement of each needle through the needle guide into the tissue and advancement of the ampule or cartridge to force the sclerosing agent or other medicament through the needle. Thereafter, the needle assembly may either be withdrawn or relocated to another position for injection of medicament through the same or other needle advancing through the same needle guide into the opposite cornul portion.

This is a continuation application of Ser. No. 594,269, filed July 9,1975 now U.S. Pat. No. 4,136,695, and entitled TRANSVAGINALSTERILIZATION INSTRUMENT AND METHOD OF STERILIZATION.

BACKGROUND OF THE INVENTION

This invention relates to a novel and improved method for the blindinjection of medical solutions into one or more predetermined locationswithin a cavity of the body; and more particularly relates to a novelmethod for occluding the fallopian tubes for sterilization of females ina rapid, safe and efficient manner.

Various methods and techniques have been devised and utilized over theyears for sterilization or birth control of females. Innumerable typesof contraceptives have been suggested and utilized as a temporary meansof birth control but have never been found to be completely effective.Similarly, although certain drugs have been found to be an effectivemeans of temporary sterilization or birth control, side effects of thesedrugs is at best uncertain. In any case, none of the temporary means ofsterilization or birth control proposed is capable of providing longtermsterilization and requires either regular use or dosages in order to beeffective. Of course, surgical procedures are in use which will achievepermanent sterilization but in most all cases cannot be resorted to as ameans of longterm temporary sterilization or birth control.

It is well known that a common cause of sterility is the blockage of theFallopian tubes by inflammation, and it follows that an ideal method ofsterilization would be the transvaginal introduction of an inflammatoryagent which would occlude the cornul portion of the tubal lumen, sinceat this location in female mammals there is found a narrow canal onopposite sides of the uterus which is surrounded by dense and highlytonic uterine muscles resembling a sphincter. The principal difficultiesinherent in this approach to sterilization are not only the utilizationof an inflammatory agent which will reliably produce the necessaryocclusion but in the method and instrumentation of introducing the agentin a blind fashion so as to assure in each case that the injection ismade at precisely the proper location without pain or injury to thepatient. Moreover, it is highly desirable that the inflammatory agent beinjected on both sides of the uterus.

Studies conducted to date have demonstrated the ability to inject underdirect vision into the uterine cornus of certain female mammals asclerosing agent which would produce scarring in animal tissue, i.e., achronic lesion over fairly extended time periods. Here, reference ismade to my earlier publications jointly with other authors whichdescribe earlier work done in the field of female sterilization;"Transvaginal Delivery of Sterilizing Chemicals" Human Sterilization,(1972); "Chemical Occlusion at the Uterotubal Junction in Monkeys,"American Journal of Obtetrics Gynec., (1972); "Evaluation ofExperimental Methods of Occluding the Uterotubal Junction," FemaleSterilization (1972). In the selection of a sclerosing agent,particularly good results were realized through the use ofparaformaldehyde or polyoxymethylene adminstered in an alcohol solutionand injected into the uterine wall in the region of the Fallopian tubesostra. Specifically, the results of more recent testing with the use ofparaformaldehyde solutions revealed longterm sterilization for periodsas great as six weeks with little or no apparent side effects, and madeapparent the desirability for a safe, reliable method and instrument forbilateral injection of the solution at precise locations in the uteruswithout benefit of visibility or physical touch and solely bymanipulation and control of the instrument externally of the vagina.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide for anovel and improved method for sterilization of females which is safe anddependable in use and is capable of achieving long-term but temporarysterilization in a simplified, rapid and efficient manner.

It is another object of the present invention to provide for a novel andimproved hypodermic needle assembly which will assure accuratepositioning and guidance of a hypodermic needle into position for theblind injection of an inflammatory agent at the cornul portion of thetubal lumen; and a needle assembly which is capable of bilateral, blindinjection of an inflammatory or sclerosing agent into the cornul portionon opposite sides of the uterus.

It is a further object of the present invention to provide for ahand-held hypodermic needle assembly which can be easily manipulatedwith one hand for insertion of the needle into position internally ofthe uterus, penetration of the needle into the tissue, injection of theinflammatory agent through the needle, and withdrawal of the needle fromthe tissue, followed by a repetition of the same sequence of steps onthe opposite side of the uterus without removal of the entire needleguide assembly for repositioning or relocation of the needle.

It is another object of the present invention to provide for ahypodermic needle assembly which facilitates positioning and selectiveextension of one or more needles and injection of selected quantities ofan inflammatory agent into different selected locations in the uterus incarrying out female sterilization procedures; and further wherein thehypodermic needle can be composed at least in part of disposableelements which are so constructed as to prevent contamination of theneedle or accidental introduction of air into the needle guide when theneedle is injected into the tissue.

It is a still further object to provide in a hypodermic needle assemblyfor a novel and improved means for selective manipulation of one or moreneedles and disposable cartridges in such a way that the assembly can begrasped with one hand and simultaneously manipulated with the otherhand; and further wherein the needle assembly is lightweight, composedof a minimum number of parts and facilitates grasping and handling witha minimum number of operations required for the insertion, penetrationof the needle and injection of the sclerosing agent.

In accordance with the present invention, long-term sterilization isachieved by the blind injection into the uterus of a sclerosing agent atthe cornul portion of the tubal lumen on opposite sides of the uterus.The preferred method by which the same is accomplished comprises thesteps of inserting a hypodermic needle assembly into the uterus with aneedle guide disposed for extension at a predetermined angle to thelongitudinal axis of the assembly, the guide being of a predeterminedlength and attitude so as to move safely into contact with the cornulportion without danger of injury to the wall or lining of the uterus.Upon insertion of the needle guide, one or more needles may beselectively advanced through a rupturable film which normally closes theend of the guide to penetrate the tissue at the cornul portion, followedby injecting a sclerosing agent through the needle to produce a chroniclesion at that point and consequent blockage of the fallopian tubes.Upon injection of the agent, the needle is withdrawn from the tissue andthe needle guide turned or rotated into engagement with the cornulportion on the opposite side of the uterus and the foregoing procedureof penetration of the needle and injection of the agent repeated. Theentire procedure can be carried out by a needle assembly which not onlyassures accurate placement of the needle guide and needle withoutbenefit of visibility or touch but also permits holding and manipulationof the needle and syringe with one hand so as to leave the other handcompletely free to steady and hold the needle assembly in place.

In the construction of the hypodermic needle assembly, one or moreneedles can be selectively advanced through the needle guide either forsimultaneous or successive penetration into the body tissue. In the onemodified form of invention, a double needle assembly has been devised inwhich each needle is disposed for independent advancement through acommon needle guide and each needle is operatively associated with aseparate syringe or cartridge for injection of the sclerosing agentthrough that needle. The double needle enables use of a separate needleand cartridge for each cornul portion without removal of the entireassembly from the uterus. In still another modified form of invention, atri-needle assembly has been devised in which three needles aresimultaneously advanced to penetrate an enlarged area of the cornulportion followed by injection of the agent from a single cartridgesimultaneously through the three needles.

Additional features of the needle assembly in clude mounting anddisposition of single or plural needles in the needle guide as well asthe cooperative disposition of one or more disposable cartridges in acommon housing. A unique form of finger-engaging needle support andguide are provided to greatly facilitate handling and manipulation ofthe needles while assuring that the needles remain in position as thesclerosing agent is injected therethrough into the tissue. The entireassembly except for the needle can be constructed of lightweight plasticmaterial requiring a minimum number of parts which are well balanced andeasy to manipulate in use. In addition, the assembly facilitates the useof a cartridge of the piston/cylinder type which enables operation andcontrol with one hand.

The above and other objects, advantages and features of the presentinvention will become more readily appreciated and understood from aconsideration of the following description when taken together with theaccompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of one form of hypodermic needle assembly illustratingsuccessive placement of the needle guide within the uterus in carryingout the method of the present invention;

FIG. 2 is a view partially in section illustrating the form of needleguide assembly shown in FIG. 1 with the needle and cartridge in aretracted position;

FIG. 3 is a view partially in section of the first form of hypodermicneedle assembly in which the needle is advanced forwardly through theneedle guide for penetration into the body tissue;

FIG. 4 is still another illustration partially in section illustratingadvancement of the syringe or cartridge with respect to the needle inorder to inject an agent through the needle into body tissue;

FIG. 5 is an end view of the first form of hypodermic needle assemblyshown in FIGS. 1 to 4;

FIG. 6 is an enlarged view partially in section of the needle guide andtip;

FIG. 7 is a somewhat perspective showing of the manipulation of thehypodermic needle assembly in carrying out the method of the presentinvention;

FIG. 8 is a cross-sectional view of a modified form of hypodermic needleassembly employing a tri-needle arrangement within a common needleguide;

FIG. 9 is a cross-sectional view of still another modified form ofneedle assembly in accordance with the present invention showingutilization of a pair of needles and associated syringes within a commonhousing and needle guide in accordance with the present invention;

FIG. 10 is an end view of the needle guide assembly illustrated in FIG.9; and

FIG. 11 is an enlarged fragmentary view partially in section of theneedle guide and tip in the modified form of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring in more detail to the drawings, a first embodiment of thepresent invention is illustrated in FIGS. 1 to 7 and specificallyillustrates a hypodermic needle assembly 10 comprising an outer housing12, a needle guide 14 having a front generally rounded tip 15, a needle16 adapted for extension through the needle guide, a needle support 18,and a disposable syringe or cartridge 20.

As a setting for the present invention, the needle assembly 12 is shownin FIG. 1 in inserted position within the uterus as generally designatedat U and the cornul portion designated at C of a female mammal, the tip15 being illustrated in full in contacting relation to the cornulportion C of the tubal lumen on one side of the uterus. The needle guideis further illustrated in dotted form when its position is reversed andthe tip is brought into contact with the opposite side of the uterus. Incarrying out the method of the present invention, transcervical tubalocclusion is achieved by the bilateral injection of a sclerosing agentinto the cornul portions of the tubal lumen on opposite sides of theuterus. In order to produce a chronic lesion at the cornul portions, apreferred form of sclerosing agent is a sixteen molar suspension ofparaformaldehyde in alcohol. Paraformaldehyde or polyoxymethylene is asolid, long chain polymerization of the aldehyde methanal. It has achemical formula of (CH₂ O)_(n) and a molecular weight of (30.03)_(n)and is preferably administered in a suspension of absolute ethanol (C₂H₅ OH, M.W. 46.07) which can be injected into the uterine wall in theregion of the fallopian tube ostia without producing undesirable sideeffects. Molar suspensions of paraformaldehyde in absolute ethanol areprepared in 10 ml. portions. For a sixteen molar suspension, 4.8078grams of paraformaldehyde are added to the ten ml. of ethanol. The molarconcentration possibly could vary between twenty molar and ten molardepending upon optimal effects of the human uterus. In preparations formonkeys, sixteen molar was found to be the optimal concentration. Mostdesirably a high grade paraformaldehyde is used such as the "BakerGrade" sold by the J. T. Baker Chemical Company.

The paraformaldehyde solution is placed in a disposable cartridge 20 andas a preliminary to insertion of the needle guide assembly into theuterus, the position of the uterus is determined by a bi-manualexamination and a bivalve speculum inserted into the vagina. The cervixis washed with aqueous zepherin solution and a tanaculum placed in theanterior lip of the cervix. The cervix may be probed with a uterinesound to determine patency. Following this, the needle guide is insertedand advanced until the tip reaches the cornul portion. The needle isthen advanced on the order of five millimeters and 0.5 cc of thesclerosing solution injected slowly over a fifteen second period oftime. The needle is then withdrawn into the needle guide, the guiderotated or reversed to the opposite side of the uterus and the sameprocedure repeated without removing the needle guide from the uterinecavity.

Considering in more detail the construction and arrangement of the formof needle assembly shown in FIGS. 1 to 7, the housing 12 is ofthin-walled, elongated hollow cylindrical configuration being open atits rearward end 24 and having a closed forward end 25. The forward end25 terminates in a beveled end portion or nose 26, the end beingthick-walled and provided with an inner inclined wall surface 27 and aflat central surface portion 28 disposed normal or perpendicular to thelongitudinal axis of the housing. A guide passage 29 extends axiallythrough the forward end 25 of the housing for the purpose of anchoringrearward end 32 of the needle guide 14. The inner wall surface of thehousing 12 includes axially spaced, annular ribs 33 and 34, theuppermost rib 33 being located adjacent to the rearward open end 24 andthe lower rib 34 being located adjacent to and just rearwardly of theinner inclined surface 27 of the forward end 25. In addition,finger-engaging lobes or flange portions 36 are arranged at equallyspaced circumferential intervals around the rearward end 24 of thehousing, there being a series of three lobes or flange portions 36extending radially outwardly from the wall of the housing as illustratedin FIG. 5 to facilitate grasping of the end of the outer housing.

The needle guide 14 serves as a means of guiding forward extension ofthe needle 16 in a predetermined direction laterally away from thelongitudinal axis of the needle assembly. For this purpose, the needleguide is comprised of a thin-walled, substantially rigid tubular portionhaving its rearward end 32 permanently affixed within the guide passage29 of the front end of the housing and having a forward end 38 whichundergoes a gradual bending or curvature away from the longitudinal axisat an angle approximating 10°-15°. The tip 15 of the needle guide is inthe form of a bulbous or rounded, relatively thick-walled sleeve havinga central bore 40 of a diameter corresponding to the inner diameter ofthe needle guide 14, and the diameter of the bore 40 is increased as at40' to permit snug-fitting insertion of the forward end 38 of the needleguide 14 into the tip 15. The rounded tip 15 is securely bonded to theend of the needle guide so as to be integrally united thereto with thebore 40 forming a continuation of the forward end 38. In addition, acoating 42 which is in the form of a plastic sheath or covering coversthe end of the tip 15 so as to seal the bore 40 against entry of bodysecretions when the needle guide is inserted and also serves to preventloss of the alcohol from the sclerosing agent prior to penetration ofthe needle into the body tissue; otherwise, when the solution-filledneedle is in contact with the uterine contents, because absolute ethanolalcohol is a dehydrating agent, as soon as it comes into direct contactwith blood and fluid in the uterine cavity, it is drawn out of theneedle leaving only a precipitate of paraformaldehyde crystal pluggingthe needle. Coating of the tip with a plastic film which will occludethe needle aperture at the distal end of the probe avoids this problem;and when the probe is fixed in the cornu the needle may be advancedthrough the film and into the muscle and the suspension or sclerosingagent injected without delay.

As shown in FIGS. 2 to 4, the needle 16 is conventionally constructed ofa thin-walled, tubular hypodermic needle composed of stainless steel orsimilar material of the desired gauge, the needle being of a length toextend through the major length of the housing 12 and through the needleguide 14, and an intermediate portion 44 is fixed within a sleeve 45which is mounted within a central bore 46 in the needle support 18. Theforward section 16' of the needle projecting forwardly of the sleeve 45is of a length such that when the needle support 18 is in a retracted orraised position as shown in FIG. 2 the pointed end 48 of the needle isaligned with the forward extremity of the tip 15; and when the needlesupport member is advanced forwardly into abutment with the innersurface of the front end 25 of the housing, the forward pointed end ofthe needle will advance beyond the tip for a distance of fivemillimeters so as to safely penetrate the body tissue and muscle at thecornul portion. The needle also includes a rearward extension 16" whichextends rearwardly from the forward end of the needle support andextends for the greater length of the housing so as to terminate in apointed end 49 normally spaced in front of the end of the disposablecartridge 20.

The needle support 18 serves to control axial advancement of the needlethrough the needle guide 14 as well as to lock the needle in itsretracted and extended positions. To this end, the needle support 18includes a hollow cylindrical portion 50 extending rearwardly from thefront end of the needle support in spaced inner concentric relation tothe housing 12 and terminates at its rearward end in spaced, radiallyoutwardly projecting, finger-engaging lobes 52. The finger-engaginglobes or flange portions 52 are so aligned with respect to the lobes 36on the housing as to be evenly spaced therebetween; and as shown in FIG.5 are arranged at equally spaced circumferential intervals between thelobes 36. The needle support is centered with respect to the housing bymeans of the ribs 33 and 34 on the housing wall; and the externalsurface of the cylindrical wall 50 is provided with axially spacedannular grooves 53 and 54, the groove 53 receiving the rib 33 in orderto lock the needle in its advanced position projecting from the tip, andthe groove 54 receiving the rib 33 in order to lock the needle in itsretracted position. Movement of the needle between its retracted andadvanced positions is of course controlled by manipulation of thefinger-engaging lobes 52 and facilitates grasping of the underside ofthe lobes 36 between the thumb and middle fingers while pressing down onthe lobes 52 with the forefinger to urge the needle forwardly throughthe needle guide until the rib 33 is locked in place in the rearwardmostgroove 53.

The disposable cartridge 20 may be of conventional construction and asillustrated in FIGS. 2 to 4 is of the piston/cylinder type having anouter vial or ampule 60 which contains the liquid medicine and a groovedplunger 62 provided with a hollow bore 63 opening at its rearward endinto the vial and closed as at 64 at its opposite forward end. Theforward end 64 includes a centrally located diaphragm 65 which is easilyruptured by the pointed end 49 of the needle when the cartridge isadvanced forwardly through the needle support 18. The cartridge isguided in its forward advancement by a hollow cylindrical guide portion66 directed rearwardly from the inner surface of the front end of theneedle support in inner spaced concentric relation to the outer wall 50and to the cylindrical wall 61 of the cartridge 20 and which threadedlyengages the external surface of the plunger 62. The construction of thecartridge is conventional and for example may be of the typemanufactured and sold by Bristol Laboratories of Syracuse, N.Y., underthe trademark "Abboject Syringe," Model No. NDC 0074-4916-01 except thatthe dimensioning and configuration are modified and reduced forinterworking with the needle support and housing. In this relation, thedisposable cartridge is readily installed by inserting the plungerwithin the cylindrical wall 66 and threading into position. Thereafter,forward advancement of the cartridge by depressing the vial 60 willcause the pointed end of the needle 49 to rupture the diaphragm 65 andto move into liquid communication with the interior of the plunger 62.Continued advancement of the vial will force the liquid within the vialthrough the central bore 63 in the plunger and through the interior ofthe needle for injection into the tissue. The external surface of thecartridge 20 is provided with suitable graduations to measure the amountof agent injected in accordance with conventional practice. Thecartridge 20 may readily be replaced by unthreading the plunger from thewall support 66 and replacing with a new cartridge, although it will beapparent that the entire needle assembly may be comprised of disposableelements and normally would not be designed for repeated use.

In the modified form of needle assembly illustrated in FIG. 8, likeparts are correspondingly enumerated, the modification residing in aseries of three needles 70, 71 and 72 arranged for slidable extensionthrough the needle guide 14, the needles 70-72 terminating at theirrearward end in a common manifold 74 which is affixed to the forward endof a single needle section 75 extending through the needle support 18and affixed to the needle support at 44. The manifold 74 establishesliquid communication between the rearward needle section 75 and theforward needles 70-72, and at the same time defines a coupling betweenthe needle section with the rearward needle section having its forwardend firmly anchored in one end of the manifold 74 and the needlesections 70-72 having their rearward ends firmly anchored in theopposite or forward end of the manifold. The guide passage 29' in thefront end 25' of housing 12' is slightly enlarged to accommodate agreater size or diameter of needle guide 14', but in other respects theconstruction of the housing 12' corresponds to that described in thefirst form shown in FIGS. 1 to 7. Similarly, the needle support 18corresponds to the needle support shown in the first form.

The needles 70 to 72 each terminate in a front pointed end disposed inapertures 77 in the rounded tip 76. The rounded tip 76 at the end of theneedle guide 14' differs from the tip 15 of the first form in thatseparate guide passages or apertures 77 are formed at equally spacedcircumferential intervals branching or radiating out at a slight anglefrom the front extremity of the needle guide so as to function as guidechannels for forward divergent movement of the pointed ends of theneedle through the tip in penetrating into the skin. The angle ofdivergence between the apertures or guide channels 77 is very slight,preferably being on the order of less than 5° with respect to the axisof the needle guide but sufficient to insure spacing between the pointedends of the needles in penetrating the body tissue. In this way, whenthe sclerosing agent is injected through the needles it is disseminatedover a wider area to assure a greater region of scarring or lesion atthe cornul portion. However, the total quantity of sclerosing agentinjected corresponds to that previously described.

In the other modified form of invention shown in FIGS. 9 to 11, a doubleneedle assembly is illustrated. However, its intended use and functiondiffers from that of the tri-needle concept described with respect toFIG. 8 in that each needle is equipped with a separate cartridge orsupply of sclerosing agent and each is adapted to be independentlyactivated so that a separate needle can be used for injection into eachcornul portion without necessity of removing the needle assembly fromthe uterus. In the modified form of invention as shown, an outer housingtakes the form of a hollow thin-walled casing 80 of generallyoval-shaped, cross-sectional configuration having radially outwardlyextending flange portions 81 and 82 at opposite ends of the major axisof rearward open end of the casing. The casing may be of uniformcross-section throughout its length and at its forward end has an endcap 83 provided with a forwardly tapered nose 84 and a guide ring 85mounted at the rearward end of the end cap adjacent to its point ofattachment to the forward end of the housing. The housing is dividedinto two separate symmetrical chambers by a central wall or divider 86extending the substantial length of the housing and tapering forwardlyso as to terminate at its forward end in inner spaced concentricrelation to the needle guide ring 85. The end cap 83 includes an axiallyextending guide passage 87 to receive the rearward end of needle guide88 which is permanently affixed such as by bonding to the wall of theguide passage and terminates at its forward extremity in a tip 89 havinga pair of laterally spaced apertures or guide channels 90 incommunication with the interior of the needle guide. A pair of needles92 are disposed for slidable extension through the needle guide andterminate in front pointed ends 93. In turn, rear pointed ends 94diverge rearwardly through the casing and each extends into chamber 95formed at the forward or leading end of a needle support portion 96.Each needle support 96 is of hollow generally cylindrical configuration,except for its leading end, and contains an axially extending needlesection 98 in liquid communication with the chamber 95 and in offsetrelation to the rearward extremity 94 of each needle 92, the rearwardneedle section 98 extending rearwardly along the longitudinal axis ofeach respective needle support. Each needle support 96 is slidablydisposed within a retainer ring 100 on each side of the divider 86, eachring 100 terminating at its front end in an inwardly protruding annularrim or lip 101 so as to limit forward movement of the needle support 96.An external rib 97 on each needle support is slidable within alongitudinal slot 99 in the guide ring 100 to limit outward movement ofthe needle support with respect to the housing. The rearward open end ofeach needle support has a radially outwardly projecting, finger-engagingtab 104 projecting beyond the outer edge of the lobes 81.

Each of the needle supports 96 is designed internally in the same manneras the first form of needle support described with reference to FIGS. 1to 7 for the purpose of receiving a conventional form of disposablecartridge 106 through its rearward open end. In the manner previouslydescribed with reference to FIGS. 1 to 7, each disposable cartridge isslidably disposed in axial alignment with a rearward needle section 98,and upon depression of the cartridge will cause the needle section torupture the diaphragm at the leading end of the cartridge to establishcommunication with the interior of the cartridge vial.

In operation, after first inserting the needle assembly in place, one ofthe needles is activated by depressing one of the needle supports 96 tocause forward advancement of the needle tip 93 through the tip of theneedle guide 88. The cartridge 106 associated with that needle supportis then depressed to rupture its diaphragm and by continued inwardforcing cause a selected amount of sclerosing agent to be injectedthrough the associated needle. The needle is then withdrawn or retractedby lifting up the finger-engaging tab 104 and repositioning the needleassembly into alignment with the opposite cornul portion. The otherneedle is then advanced and the sclerosing agent injected through theneedle into the other cornul portion and the entire assembly removed.Again a plastic film or covering 42 is applied over the end of the tip89 to prevent accidental loss of the alcohol in the sclerosing agent asearlier described.

From the foregoing, it will be appreciated that a unique method andmeans have been devised for female sterilization which permits blind,accurate injection of a sclerosing agent into the cornul portions of theuterus and consequent blockage of the fallopian tubes. The length andcurvature of the needle guide in each case is such as to assure accurateplacement of the assembly without injury to the uterine wall and whileassuring smooth advancement of the needle into the tissue as apreliminary to injection of the agent. The needle assembly as describedfurther facilitates bilateral injection of the sclerosing agent andminimizes the components and steps required in carrying out theprocedure. It is to be understood that various modifications and changesmay be made in the method and apparatus of the present invention withoutdeparting from the spirit and scope thereof as defined by the appendedclaims and reasonable equivalents thereof.

What is claimed is:
 1. The method of transcervical sterilization offemales comprising the steps of:(a) blindly inserting a plurality ofneedles into the uterus for a distance to penetrate the body tissue atone of the cornul portions on one side of the uterus; (b) injecting asclerosing agent composed of paraformaldehyde in an alcohol solutionthrough the needles into the body tissue from a point externally of theuterus in a concentration sufficient to occlude the cornul portion onthe one side of the uterus; (c) withdrawing the needles from the tissueand relocating them in the body tissue of the opposite cornul portionand injecting a predetermined amount of said sclerosing agenttherethrough and into the body tissue at that point; and (d) withdrawingthe needles from the uterus.
 2. The method according to claim 1 in whicha plurality of needles are simultaneously advanced through a commonneedle guide into the body tissue at each of the cornul portions.
 3. Themethod according to claim 1 in which a plurality of needles aresuccessively advanced through a common needle guide for penetration ofthe body tissue at each of the cornul portions.